1. Field of the Invention
The invention relates generally to testing of packaging seals. More specifically, the invention relates to evaluation of seal testing results.
2. Background of the Invention
The packaging of sterile products such as medical devices must be manufactured according to strict specifications in order to prevent contamination of the product. The packaging for these products often includes one or more seals where portions of the packaging are bonded. A variety of specifications and regulations are directed toward the integrity of these seals. As a result, the manufacturers and users of this packaging often must have access to technology for testing these seals.
There are a variety of methods and devices available for testing packaging seals. The two most common are peel testing and burst testing. Peel testing is performed by cutting the package into a several pieces that each have a portion of the seal. The seal on each piece is pulled apart at a constant velocity while measuring the force on the seal. Peel testing is known to provide reliable seal integrity results. However, because the packaging must be cut into several pieces that are each tested independently, evaluating the integrity of the seal on a single packaging can take a long time. Additionally, the testing can miss the weakest part of the seal.
Burst testing includes inflating the packaging with a fluid until the seal bursts. The most common methods involve recording the maximum pressure reached before the package seal ruptures. Although burst testing has proven to be a quicker test, the results are often unreliable. Additionally, there is currently not a reliable method available for comparing burst test results with peel test results. For the above reasons, there is a need for a reliable burst test and a need for a method of processing the results so they can be compared with peel test results.
The invention relates to a method for evaluating a seal on a package. The method includes determining the value of a burst test force parameter. The burst test force parameter being a parameter that results from a force placed on the package during a burst test. The method also includes using the value of the burst test force parameter to determine a value of a peel test force parameter for the package. The peel test force parameter being a parameter that results from a force placed on the package during a peel test.
Another embodiment of the method includes using the value of the burst test force parameter to determine a seal integrity. The seal integrity is a value that is determined using a peel test under specific parameters to evaluate the quality of the seal. Because the peel test seal integrity is determined using a peel test, the method allows burst test results to be converted to a seal integrity value that can be compared with the seal integrity values that are generated directly from peel tests. Hence, an embodiment of the method allows for comparison of burst test results and peel test results.
The invention also relates to data for use with a seal testing device. The data includes burst test force parameter values related to peel test force parameter values. The relation indicates the burst test force parameter value and the peel test force parameter value that would result from performing a burst test and a peel test such that a seal would peel at substantially the same velocity during the burst test and during the peel test.
The invention also relates to a database for use with a seal testing device. The database includes a plurality of burst test force parameter values and a plurality of peel test force parameter values. Each peel test force parameter value is associated with one of the burst test force parameter values. Additionally, an associated peel test force parameter value and burst test force parameter value result from a burst test and peel test performed such that a seal would peel at substantially the same velocity during the burst test and during the peel test.
Another embodiment of a database for use with a seal testing device includes a plurality of seal velocity values and a plurality of peel test force parameter values. Each peel test force parameter value is associated with one of the seal velocity values and results from performing a peel test at the associated peel velocity. In one embodiment of the invention, a plurality of these databases are each associated with a seal integrity. The plurality of databases can be arranged in a three dimensional database.
The invention also relates to a method of preparing data for use with a seal testing device. The method includes performing a burst test and a peel test such that a type of seal on a type of package peels at substantially the same velocity during the peel test and the burst test. The method also includes evaluating a burst test force parameter value that results from a force applied to the package during the burst test and evaluating a peel test force parameter value that results from a force applied to the package during the peel test. The method further includes storing the value of the burst test force parameter such that it is associated with the value of the peel test force parameter.
Another method of preparing data for use with a seal testing device includes performing a plurality of peel tests on packages that each have the same seal integrity rating. Each peel test is performed at a different peel velocity. The method also includes evaluating a peel test force parameter value resulting from each peel test. The method further includes storing the peel test force parameter values such that the peel test force parameter value for a particular peel test is associated the with the peel velocity at which the particular peel test was performed. In one embodiment of the invention, this method is repeated for packages having different seal integrities. This embodiment can further include storing the peel test force parameters and the associated peel velocities such that the peel test force parameters and the associated peel velocities are associated with a seal integrity.